With moobies now but a memory on his 9.5 percent body-fat frame, Peterson has Porsches lining up outside the hillside L.A. house he converted into a gym known simply as the Compound. Keeping the paparazzi-proof sanctuary stocked with Oribe hair-care products and monogrammed towels, Peterson, 42, leads clients such as Ben Affleck, Penélope Cruz and Debra Messing through intense custom-tailored routines. "When my clients are here, it's 60 minutes of pure go, go, go," says Peterson, whose new book, G-Force: The Ultimate Guide to Your Best Body Ever, details: his take-no-prisoners philosophy. "There's no hanging around the watercooler chatting."
And no behaving like the chubby Houston-bred 10-year-old did when his mom enrolled him in Weight Watchers. "At one meeting they announced I'd lost 5 lbs.," he says. "I celebrated by buying two ice-cream sandwiches." He dropped the weight after graduating from Duke University in 1984 and getting serious about fitness. Five years later he was working as a movie production assistant in L.A. when a fellow gym rat offered to pay him for training—and a career was born.
Nowadays Peterson—who lives with wife Janet and their three kids—rises at 3 a.m. to train himself. By 6 he's punishing clients. "Everyone is an extremely hard worker," he says. "It's no coincidence that all of them are at the top of the food chain."